This question is prompted, no doubt, by the freakin’ humidity and the fact that I really need a haircut!
When I go too long between haircuts, certain things always happen. For example, when the bangs on the right side of my head reach a certain length (like, down to about my cheek bone – I told you I needed a haircut!), that piece of hair flips up on the end, with the ends sticking straight forward.
Now, I understand that hair grows from a foliicle. What I can’t understand is why the curl doesn’t appear until it hits a certain length. Since it always happens and therefore seems to be a characteristic of my hair, it would seem that the curl would be there when the hair emerged from the follicle, since the end is what curls. But that doesn’t make sense either, because when I do get my hair cut, that curl will be cut off, and as soon as my hair gets too long again, it will reappear.
I don’t know anything about the subject, but I would guess that it takes a certain minimum weight, that is, length of hair to start pulling the hair fiber into a curl. The shape of the follicle determines to some extent the natural shape of the hair shaft, but other factors like hair length, humidity, grooming, etc. all affect how the cells in the hair shaft are stressed and thus the overall shape of the fiber.
My hair behaves very similarly. I used to think it was stick straight–back when I wore it short for years. Then a few years ago I began growing it long for the first time since I was a child and I was amazed to see waves appearing in my hair. It seems at shoulder length my hair has a really fun light curl to it. Now I keep it medium length, but I’ve noticed when I cut my bangs into a slide bang or cut layers into it they tend to be straighter.
So you’re not the only one with straight hair when short and curlier hair when longer.
Funny, I have the opposite problem - my hair is quite curly and hard to manage when short (and here in South Florida, where the humidity is high, I’ve pretty much resigned myself to a permanent semi-wave), and as it grows, it gets progressively less frizzy (although it never does quite go back to the same straightness that I had before I hit puberty).
Here’s a totally WAG, and it might be absolutely wrong:
There might be a specific component of your hair that keeps it straight. The hair at the end is obviously older than the hair at the scalp, and has been washed/conditioned/brushed/whatever many more times. Is it possible that the straightening component gets removed or somehow breaks down, causing the curl? You do a lot of things to your hair during the length of time it takes it to grow that long.